JP7074131B2 - Vinyl sulfone compound, electrolytic solution for lithium ion battery and lithium ion battery - Google Patents

Description

The present invention relates to a vinyl sulfone compound, an electrolytic solution for a lithium ion battery, and a lithium ion battery, and is particularly excellent in storage stability when stored for a long period of time in a non-aqueous solvent, and when used in a lithium ion battery, the temperature is high. The present invention relates to a vinyl sulfone compound or the like, which can improve the decrease in capacity after a storage test and improve the cycle characteristics related to the life and the initial charge / discharge efficiency.

In recent years, the demand for energy saving has been particularly increasing, and the technology related to electricity storage has become important. As the battery used for power storage, a lithium ion battery, a sodium ion battery, a nickel hydrogen battery and the like are known. Among the batteries, the lithium ion battery is used for various purposes such as in-vehicle use and power supply for mobile phones because of its high energy density and low cost per unit capacity.

Lithium-ion batteries are expected to be used for various purposes in the future in addition to the above-mentioned applications. For example, it is expected to be used as a power source for wearable or flexible electronics such as smart glasses, smart watches and organic EL lighting, and to be used in a high temperature environment, and further ensuring safety is required.

As the lithium ion battery, for example, an electrolytic solution-based lithium ion battery composed of a positive electrode, a negative electrode, a separator, a non-aqueous electrolytic solution containing a lithium salt, and the like is known.
Further, a so-called all-solid-state lithium-ion battery, which is composed of an electrolyte formed from a solid material without using an electrolyte of a non-aqueous electrolyte solution, is also known.
As a lithium ion battery using such a solid electrolyte, the electrolyte contains a vinyl sulfone compound having a hydroxy group (OH group) (comparative compound 1 having the structure shown below), so that the ion conductivity is high. Disclosed is a technique for making a secondary battery having no liquid leakage and excellent discharge characteristics at a low temperature (see, for example, Patent Documents 1 to 3).

However, the above-mentioned vinyl sulfone compound having a hydroxy group has poor long-term storage stability in a non-aqueous solvent, and when stored in a solution state for a long period of time, there is a problem such as generation of a precipitate (precipitate). Further, in the lithium ion battery using the vinyl sulfone compound having a hydroxy group, the decrease in capacity after the high temperature storage test, that is, the life is a problem.

Japanese Unexamined Patent Publication No. 2000-17706 Japanese Unexamined Patent Publication No. 2000-21446 Japanese Patent Application Laid-Open No. 2002-190323

The present invention has been made in view of the above problems and situations, and the problem to be solved thereof is excellent storage stability when stored for a long period of time in a non-aqueous solvent, and when used in a lithium ion battery, the temperature is high. It is an object of the present invention to provide a vinyl sulfone compound capable of improving the decrease in capacity after a storage test and improving the cycle characteristics related to the life and the initial charge / discharge efficiency. Further, the present invention provides an electrolytic solution for a lithium ion battery and a lithium ion battery.

In the process of investigating the cause of the above problem in order to solve the above-mentioned problems, the present inventor has added the hydroxy group to a specific substituent, particularly the number of carbon atoms, in the above-mentioned vinyl sulfone compound having a hydroxy group (comparative compound 1). By substituting an acyl group of 4 or less, it has an excellent long-term storage stability in a non-aqueous solvent by predominantly acting on the interaction and film formation on the surface of the negative electrode or the positive electrode, and the lithium ion battery after the high temperature storage test. We have found that the decrease in capacity is improved, the cycle characteristics are improved, and the initial charge / discharge efficiency is improved, and the present invention has been made.
That is, the above-mentioned problem according to the present invention is solved by the following means.

［一般式（Ｉ）において、Ａは、シクロヘキサン環、ベンゼン環、ピリジン環又はフラン環を表す。Ｒ_１は、下記一般式（II）又は下記一般式（III）を表す。］

［一般式（II）において、Ｒ_２は、水素原子、ハロゲン原子で置換されていてもよい、アルキル基、シクロアルキル基、ハロゲン原子若しくはアルキル基で置換されていてもよい、アリール基、アルコキシ基、アリールオキシ基又は－ＮＲ_４Ｒ_５を表す。Ｒ_４及びＲ_５は、アルキル基又はアリール基を表す。－＊は、酸素原子との結合を表す。
一般式（III）において、Ｒ_３は、アルケニル基、アルキニル基、ハロゲン原子で置換
されていてもよい、アルキル基若しくはシクロアルキル基、ハロゲン原子若しくはアルキル基で置換されていてもよい、アリール基、アルコキシ基、アリールオキシ基又は－ＮＲ_４Ｒ_５を表す。Ｒ_４及びＲ_５は、アルキル基又はアリール基を表す。－＊は、酸素原子との結合を表す。］

［一般式（IV）において、Ｒ _６ は、水素原子、アルキル基、ビニルスルホニル基を有するアルキル基、又は、ハロゲン原子を有するアルキル基を表す。Ｒ _１ は、前記一般式（Ｉ）におけるＲ _１ と同義である。］ 1. 1. A vinyl sulfone compound having a structure represented by the following general formula (I) or a structure represented by the following general formula (IV) .

[In the general formula (I), A represents a cyclohexane ring, a benzene ring, a pyridine ring or a furan ring . R ₁ represents the following general formula (II) or the following general formula (III). ]

[In the general formula (II), R ₂ may be substituted with a hydrogen atom or a halogen atom, an alkyl group, a cycloalkyl group, a halogen atom or an alkyl group, an aryl group or an alkoxy group. , Aryloxy group or -NR ₄ R ₅ . R ₄ and R ₅ represent an alkyl group or an aryl group. -* Represents a bond with an oxygen atom.
In the general formula (III), R ₃ may be substituted with an alkenyl group, an alkynyl group, a halogen atom, an alkyl group or a cycloalkyl group, a halogen atom or an alkyl group, an aryl group, Represents an alkoxy group, an aryloxy group or -NR ₄ R ₅ . R ₄ and R ₅ represent an alkyl group or an aryl group. -* Represents a bond with an oxygen atom. ]

[In the general formula (IV), R ₆ represents an alkyl group having a hydrogen atom, an alkyl group, a vinylsulfonyl group, or an alkyl group having a halogen atom. R ₁ is synonymous with R ₁ in the general formula (I) . ]

2 . The vinyl sulfone compound according to Item 1 _, wherein R6 of the compound having a structure represented by the general formula (IV) is a hydrogen atom.

3 . In the general formula (I), R ₁ is represented by the general formula (II).
The vinyl sulfone compound according to Item 1 or 2 , wherein in the general formula (II), R ₂ represents an alkyl group having 1 to 6 carbon atoms or a fluorinated alkyl group having 1 to 6 carbon atoms.

4 . In the general formula (I), R ₁ is represented by the general formula (II).
The vinyl sulfone compound according to any one of Items 1 to 3 , wherein R ₂ is an alkyl group having 1 to 3 carbon atoms in the general formula (II).

5 . In the general formula (I), R ₁ is represented by the general formula (III).
The vinyl sulfone compound according to Item 1 or 2, wherein in the general formula (III), R ₃ represents an alkyl group having 1 to 6 carbon atoms or a fluorinated alkyl group having 1 to 6 carbon atoms.

6 . The vinyl sulfone compound according to any one of items 1 to 5 , wherein the compound having the structure represented by the general formula (I) is a material added to the electrolytic solution for a lithium ion battery.

7 . An electrolytic solution for a lithium ion battery containing the vinyl sulfone compound according to any one of items 1 to 6 .

8 . Item 6. The electrolytic solution for a lithium ion battery according to Item 7 , which contains at least one of a chain carbonate and a cyclic carbonate carbonate.

9 . Item 6. The electrolytic solution for a lithium ion battery according to Item 7 , wherein the content of the vinyl sulfone compound is in the range of 0.01 to 5.0% by mass with respect to the total amount of the electrolytic solution.

10 . A lithium ion battery containing the vinyl sulfone compound according to any one of items 1 to 6 in an electrolytic solution.

11 . Item 6. The lithium ion battery according to Item 10 , which has a negative electrode made of an active material containing natural graphite or artificial graphite which is a carbonaceous material.

12 . The lithium ion battery according to claim 10 or 11 , wherein the lithium ion battery has a negative electrode made of a carbonaceous material active material containing at least one atom selected from the group consisting of Si atom, Sn atom and Pb atom.

13 . Item 2. The lithium ion battery according to Item 12 , which has a negative electrode made of a carbonaceous material active material containing a Si atom.

14 . The lithium ion battery according to any one of Items 10 to 13 , which has a positive electrode made of an active material containing any one of a lithium transition metal composite oxide and a lithium-containing transition metal phosphoric acid compound.

15 . Item 6. The lithium ion battery according to Item 14 , wherein the lithium ion battery has a positive electrode made of an active material containing a lithium transition metal composite oxide.

By the above means of the present invention, the storage stability is excellent when stored in a non-aqueous solvent for a long period of time, and when used in a lithium ion battery, the decrease in capacity after a high temperature storage test is improved, and the lithium ion battery can be used. It is possible to provide a vinyl sulfone compound capable of improving the cycle characteristics related to the life and the initial charge / discharge efficiency. Further, it is possible to provide an electrolytic solution for a lithium ion battery and a lithium ion battery using the vinyl sulfone compound.
Although the mechanism of expression or mechanism of action of the effect of the present invention has not been clarified, it is inferred as follows.
The above-mentioned vinyl sulfone compound having a hydroxy group (comparative compound 1) is likely to undergo polymerization due to an addition reaction due to the action of the hydroxy group. Therefore, when the comparative compound 1 is contained in a non-aqueous solvent, it becomes gel-like and precipitates. The thing will precipitate.
Therefore, as in the present invention, the hydroxy group is capped (cap formation; protective group formation) with the structure represented by the general formula (II) or the general formula (III), and the general formula (I) or the above general formula (I) or It is presumed that the structure represented by the general formula (IV) suppresses the polymerization due to the addition reaction. As a result, when stored for a long period of time in a non-aqueous solvent, precipitation of precipitates does not occur and the storage stability is excellent. Further, by having a substituent represented by the general formula (II) or the general formula (III) with respect to the hydroxy group, particularly an acyl group having 4 or less carbon atoms, the film easily interacts with the positive electrode or the negative electrode and is formed. Because it is moderately thin and flexible, it easily follows the expansion and contraction of the electrode itself, and when it is used as a lithium-ion battery, it not only has excellent storage stability of the electrolytic solution, but also improves the decrease in capacity after the high-temperature storage test. It is possible to improve the battery characteristics such as the cycle characteristics and the initial charge / discharge efficiency of the lithium ion battery.

The vinyl sulfone compound of the present invention has a structure represented by the above general formula (I). This feature is a technical feature common to or corresponding to the invention according to each claim.
In an embodiment of the present invention, the compound having the structure represented by the general formula (I) is soluble in a non-aqueous solvent so that the compound has the structure represented by the general formula (IV). And, it is preferable in terms of long-term storage stability in a non-aqueous solvent.

Further, in the general formula (I), R ₁ is represented by the general formula (II), and in the general formula (II), R ₂ is an alkyl group having 1 to 6 carbon atoms or 1 to 6 carbon atoms. It is preferable to represent the alkyl fluoride group of the above in terms of solubility in a non-aqueous solvent and long-term storage stability in a non-aqueous solvent, and in the case of an alkyl fluoride group, the safety of the lithium ion battery ( Nonflammable) is preferable.
Further, in the general formula (I), R ₁ is represented by the general formula (III), and in the general formula (III), R ₃ is an alkyl group having 1 to 6 carbon atoms or an alkyl group having 1 to 6 carbon atoms. Representing an alkyl fluoride group is preferable in terms of solubility in a non-aqueous solvent and long-term storage stability in a non-aqueous solvent, and in the case of an alkyl fluoride group, the safety of the lithium ion battery ( Nonflammable) is preferable.

Further, the fact that the compound having the structure represented by the general formula (I) is a material added to the electrolytic solution for a lithium ion battery is excellent in long-term storage stability of the electrolytic solution for a lithium ion battery, and lithium ions. When used in a battery, it is preferable in that it can improve the decrease in capacity of the lithium ion battery after the high temperature storage test.

The vinyl sulfone compound of the present invention is suitably used for an electrolytic solution for a lithium ion battery or a lithium ion battery.

Hereinafter, the present invention, its constituent elements, and modes and embodiments for carrying out the present invention will be described in detail. In addition, in this application, "-" is used in the sense that the numerical values described before and after it are included as the lower limit value and the upper limit value.

[Vinyl sulfone compound]
The vinyl sulfone compound of the present invention has a structure represented by the following general formula (I).

In the general formula (I), A represents a trivalent aliphatic hydrocarbon group, an aromatic hydrocarbon group or a heteroaromatic hydrocarbon group which may have a substituent.
R ₁ represents the following general formula (II) or the following general formula (III).

In the general formula (II), R ₂ may be substituted with a hydrogen atom, a halogen atom, an alkyl group, a cycloalkyl group, a halogen atom or an alkyl group, an aryl group, an alkoxy group, and the like. Represents an aryloxy group or -NR ₄ R ₅ .

In the general formula (III), R ₃ may be substituted with an alkenyl group, an alkynyl group, a halogen atom, an alkyl group or a cycloalkyl group, a halogen atom or an alkyl group, an aryl group, Represents an alkoxy group, an aryloxy group or -NR ₄ R ₅ .

_R4 and R5 in the general formula ₍ II) and the general formula (III) represent an alkyl group or an aryl group. -* Represents a bond with an oxygen atom.

Hereinafter, the general formulas (I) to (III) will be described in more detail.
In the general formula (I), the trivalent aliphatic hydrocarbon group represented by A includes acyclic or cyclic alkanes, alkenes and alkynes having 3 or more carbon atoms (for example, propane, propylene and propyne). , Butane, butane, butadiene, pentane, hexane, heptane, cyclohexane, hexene, hexin, etc.). Of these, a trivalent group derived from an alkane having 3 to 6 carbon atoms is preferable.

Examples of the trivalent aromatic hydrocarbon group include a benzene ring, a biphenyl, a naphthalene ring, an azulene ring, an anthracene ring, a phenanthrene ring, a pyrene ring, a chrysen ring, a naphthalene ring, a triphenylene ring, an o-terphenyl ring, and m-. Turphenyl ring, p-terphenyl ring, acenaften ring, coronene ring, inden ring, fluorene ring, fluorentrene ring, naphthalene ring, pentacene ring, perylene ring, pentaphene ring, picene ring, pyrene ring, pyranthrene ring, anthra entre Examples thereof include trivalent groups derived from benzene rings, tetralins and the like. Of these, trivalent groups derived from the benzene ring are preferred.

Examples of the trivalent aromatic heterocyclic group include a furan ring, a dibenzofuran ring, a thiophene ring, a dibenzothiophene ring, an oxazole ring, a pyrrole ring, a pyridine ring, a pyridazine ring, a pyrimidine ring, a pyrazine ring, a triazine ring, and a benzoimidazole ring. , Oxazole ring, triazole ring, imidazole ring, pyrazole ring, thiazole ring, indole ring, indazole ring, benzoimidazole ring, benzothiazole ring, benzoxazole ring, quinoxalin ring, quinazoline ring, cinnoline ring, quinoline ring, isoquinoline ring. , A trivalent group derived from a phthalazine ring, a naphthylidine ring, a carbazole ring, a carbazole ring, a diazacarbazole ring and the like. Of these, a trivalent group derived from the pyridine ring is preferred.

R ₁ represents the general formula (II) or the general formula (III).
Regarding R ₂ in the general formula (II), the alkyl group preferably has 1 to 15 carbon atoms, particularly 1 to 6 carbon atoms, and is, for example, a methyl group, an ethyl group, a propyl group, an isopropyl group, or butyl. Examples thereof include a group, a t-butyl group, a pentyl group, a hexyl group and the like, but more preferably, a methyl group, an ethyl group and a t-butyl group. As the cycloalkyl group, a cyclopentyl group and a cyclohexyl group are preferable.
Examples of the aryl group include groups similar to the aromatic hydrocarbon group represented by A in the above general formula (I), but a benzene ring group (phenyl group) is preferable.
The alkoxy group is preferably an alkoxy group having 1 to 6 carbon atoms, and examples thereof include a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a t-butoxy group, a pentyloxy group and a hexyloxy group, but more preferable. Is a methoxy group and an ethoxy group.
Examples of the aryloxy group include a phenoxy group and a naphthyloxy group. Examples of R ₄ and R ₅ in −NR ₄ R ₅ include an alkyl group represented by R ₂ in the general formula (II) and a group similar to the aryl group, but the alkyl group has 1 to 6 carbon atoms. Is preferable, and more preferably, it is a methyl group or an ethyl group. In addition, R ₄ and R ₅ may be connected to each other together with a nitrogen atom to form a ring.
Examples of the halogen atom as a substituent include a chlorine atom, a bromine atom, and a fluorine atom. Of these, a fluorine atom is preferable.

Regarding R3 in the general formula ( _III ), a vinyl group, an allyl group and the like are preferable examples of the alkenyl group.
As the alkynyl group, an ethynyl group is given as a preferable example.
Regarding the alkyl group, cycloalkyl group, aryl group, alkoxy group, aryloxy group, -NR ₄ R5 and halogen atom in the general formula ₍ III), the same specific examples as in the case of the above general formula (II) are used. Can be mentioned.

Further, it is preferable that the compound having the structure represented by the general formula (I) is a compound having the structure represented by the following general formula (IV).

In the general formula (IV), R ₆ represents an alkyl group, an aryl group or an alkoxy group which may have a hydrogen atom, a halogen atom or a substituent. It preferably represents a hydrogen atom or an alkyl group, and more preferably represents a hydrogen atom.
Further, in the general formula (IV), R ₁ is synonymous with R ₁ in the general formula (I).

In the present invention, in the general formula (I), R ₁ is represented by the general formula (II), and in the general formula (II), R ₂ is an alkyl group having 1 to 6 carbon atoms or the number of carbon atoms. It is preferable to represent an alkyl fluoride group of 1 to 6, and an alkyl group having 1 to 3 carbon atoms is more preferable.
Further, in the general formula (I), R ₁ is represented by the general formula (III), and in the general formula (III), R ₃ is an alkyl group having 1 to 6 carbon atoms or an alkyl group having 1 to 6 carbon atoms. It preferably represents an alkyl fluoride group.

<Exemplary compound having a structure represented by the general formula (I)>
An exemplary compound having the structure represented by the general formula (I) is shown below. These exemplary compounds are examples, and the present invention is not limited thereto.

１，３－bis(vinylsulfonyl)propan－２－ol ２０ｇ（０．０８３ｍｏｌ）、アセトニトリル５０ｍＬを窒素雰囲気下４０℃で撹拌を行った。原料が溶けたのを確認し、塩化アセチル４６ｇ（０．６ｍｏｌ）を少量ずつ滴下した。４時間撹拌後、 水２０ｍＬを加え３０分撹拌した。この反応液にジクロロメタン２０ｍＬで２回抽出し、減圧濃縮を行った。これにアセトニトリル１００ｍＬを加え６０℃で熱し溶解させた。この溶液に活性炭０．２ｇを加え２０分撹拌し、熱ろ過を行った。ろ液を１０℃で一晩静置し、析出した結晶を冷アセトニトリル２０ｍＬで２回洗浄して、収量１３ｇ（収率５１％）のアセチル体（例示化合物１）を得た。
^１H-NMR (400 MHz, DMSO-D6) δ 6.93 (dd, J = 16.5, 10.1 Hz, 2H), 6.17-6.28 (m,4H), 5.48-5.54 (m, 1H), 3.66 (q, J = 7.8 Hz, 2H), 3.56 (dd, J = 15.1, 3.7 Hz, 2H), 1.92 (s, 3H)<Synthesis example of a compound having a structure represented by the general formula (I)>
(Acetylation)

20 g (0.083 mol) of 1,3-bis (vinylsulfonyl) propan-2-ol and 50 mL of acetonitrile were stirred at 40 ° C. under a nitrogen atmosphere. After confirming that the raw material had melted, 46 g (0.6 mol) of acetyl chloride was added dropwise little by little. After stirring for 4 hours, 20 mL of water was added and the mixture was stirred for 30 minutes. The reaction mixture was extracted twice with 20 mL of dichloromethane and concentrated under reduced pressure. To this was added 100 mL of acetonitrile and heated at 60 ° C. to dissolve it. 0.2 g of activated carbon was added to this solution, the mixture was stirred for 20 minutes, and heat filtration was performed. The filtrate was allowed to stand at 10 ° C. overnight, and the precipitated crystals were washed twice with 20 mL of cold acetonitrile to obtain an acetyl compound (exemplified compound 1) having a yield of 13 g (yield 51%).
¹ H-NMR (400 MHz, DMSO-D6) δ 6.93 (dd, J = 16.5, 10.1 Hz, 2H), 6.17-6.28 (m, 4H), 5.48-5.54 (m, 1H), 3.66 (q, J) = 7.8 Hz, 2H), 3.56 (dd, J = 15.1, 3.7 Hz, 2H), 1.92 (s, 3H)

１，３－bis(vinylsulfonyl)propan－２－ol、２０ｇ（０．０８３ｍｏｌ）、ピリジン９．８ｇ（０．１２ｍｏｌ）、アセトニトリル（６０ｍＬ）を窒素雰囲気下５℃で撹拌を行った。この混合物に塩化ベンゾイル１８ｇ（０．１２ｍｏｌ）を少量ずつ加え、滴下後、ゆっくりと室温に戻していった。３０時間撹拌後、原料が残っていたので、ピリジン１．３ｇ（０．０１６ｍｏｌ）、塩化ベンゾイル２．３ｇ（０．０１７ｍｏｌ）加え、６時間撹拌行い、この反応液に水２０ｍＬを加え３０分撹拌した。酢酸エチル２０ｍＬで２回抽出を行い、減圧濃縮した。これを再結晶（酢酸エチル／メタノール＝１／９）で精製し、収量１０ｇ（収率３５％）のベンゾイル体（例示化合物５）を得た。
^１H-NMR (400 MHz, DMSO-D6) δ 7.91 (d, J = 7.3 Hz, 2H), 7.65 (t, J = 7.1 Hz, 1H), 7.51 (t, J = 7.8 Hz, 2H), 6.96 (dd, J = 16.5, 10.1 Hz, 2H), 6.13-6.19 (m, 4H),
5.75-5.81 (m, 1H), 3.86 (q, J = 7.8 Hz, 2H), 3.71 (dd, J = 15.1, 3.7 Hz, 2H)(Benzoylation)

1,3-bis (vinylsulfonyl) propan-2-ol, 20 g (0.083 mol), pyridine 9.8 g (0.12 mol) and acetonitrile (60 mL) were stirred at 5 ° C. under a nitrogen atmosphere. 18 g (0.12 mol) of benzoyl chloride was added little by little to this mixture, and the mixture was added dropwise and slowly returned to room temperature. After stirring for 30 hours, the raw materials remained, so 1.3 g (0.016 mol) of pyridine and 2.3 g (0.017 mol) of benzoyl chloride were added, and the mixture was stirred for 6 hours. To this reaction solution, 20 mL of water was added and the mixture was stirred for 30 minutes. did. Extraction was performed twice with 20 mL of ethyl acetate, and the mixture was concentrated under reduced pressure. This was purified by recrystallization (ethyl acetate / methanol = 1/9) to obtain a benzoyl compound (exemplified compound 5) having a yield of 10 g (yield 35%).
¹ H-NMR (400 MHz, DMSO-D6) δ 7.91 (d, J = 7.3 Hz, 2H), 7.65 (t, J = 7.1 Hz, 1H), 7.51 (t, J = 7.8 Hz, 2H), 6.96 (dd, J = 16.5, 10.1 Hz, 2H), 6.13-6.19 (m, 4H),
5.75-5.81 (m, 1H), 3.86 (q, J = 7.8 Hz, 2H), 3.71 (dd, J = 15.1, 3.7 Hz, 2H)

[Electrolytic solution for lithium-ion batteries]
The electrolytic solution for a lithium ion battery of the present invention (hereinafter, also referred to as "non-aqueous electrolytic solution" or "electrolyzed solution") contains a vinyl sulfone compound having a structure represented by the above general formula (I). It is a feature.
The non-aqueous electrolyte solution of the present invention is a non-aqueous electrolyte solution in which a lithium salt as an electrolyte, the vinyl sulfone compound, and other compounds, if necessary, are dissolved in the non-aqueous solvent. Further, the non-aqueous electrolytic solution may be made into a gel-like, rubber-like or solid sheet by adding an organic polymer compound or the like.

The vinyl sulfone compound contained in the non-aqueous electrolytic solution of the present invention may be used alone or in combination of two or more.
The content of the vinyl sulfone compound contained in the non-aqueous electrolytic solution of the present invention is preferably in the range of 0.01 to 5.0% by mass, and 0.1 to 2. It is more preferably in the range of 0% by mass. When it is in the range of 0.1 to 2.0% by mass, it is possible to effectively improve the decrease in capacity of the lithium ion battery after the high temperature storage test.

The non-aqueous solvent used in the non-aqueous electrolyte solution of the present invention is not particularly limited, and known non-aqueous solvents can be used.
For example, chain carbonates such as diethyl carbonate, dimethyl carbonate and ethylmethyl carbonate; cyclic carbonates such as ethylene carbonate, propylene carbonate and butylene carbonate; chain ethers such as 1,2-dimethoxyethane; tetrahydrofuran and 2-methyl. Cyclic ethers such as tetrahydrofuran, sulfolane and 1,3-dioxolane; chain esters such as methyl formate, methyl acetate and methyl propionate; cyclic esters such as γ-butyrolactone and γ-valerolactone.

The non-aqueous solvent may be used alone or in combination of two or more. In the case of a mixed solvent, a combination of a mixed solvent containing a cyclic carbonate and a chain carbonate is preferable from the viewpoint of the balance between conductivity and viscosity, and the cyclic carbonate is preferably ethylene carbonate.

The lithium salt used in the non-aqueous electrolyte solution of the present invention is not particularly limited, and known lithium salts can be used.
For example, halides such as LiCl, LiBr; perhalogenates such as LiClO ₄ , LiBrO ₄ , LiClO ₄ ; inorganic lithium salts such as inorganic fluoride salts such as LiPF ₆ , LiBF ₄ , LiAsF ₆ ; LiCF ₃ SO ₃ , Perfluoroalcan sulfonates such as LiC ₄ F ₉ SO ₃ ; fluorine-containing organic lithium salts such as perfluoroalkane sulfonic acid imide salts such as Li trifluoromethanesulfonylimide ((CF ₃ SO ₂ ) ₂ NLi) and the like. .. Of these, LiClO ₄ , LiPF ₆ , and LiBF ₄ are preferable.

The lithium salt may be used alone or in combination of two or more. The concentration of the lithium salt in the non-aqueous electrolyte solution can be in the range of 0.5 to 2.0 mol / L.

When the above-mentioned non-aqueous electrolyte solution contains an organic polymer compound to form a gel, rubber, or solid sheet, specific examples of the organic polymer compound include polyethylene oxide and polypropylene oxide. Polyether-based polymer compound; Crosslinked polymer of polyether-based polymer compound; Vinyl alcohol-based polymer compound such as polyvinyl alcohol and polyvinyl butyral; Insoluble material of vinyl alcohol-based polymer compound; Polyepicrolhydrin; Polyphosphazen; Poly Siloxane; Vinyl-based polymer compounds such as polyvinylpyrrolidone, polyvinylidene carbonate, polyacrylonitrile; poly (ω-methoxyoligooxyethylene methacrylate), poly (ω-methoxyoligooxyethylene methacrylate-co-methylmethacrylate), poly (hexafluoro) Examples thereof include polymer copolymers such as propylene-vinylidene fluoride).

The non-aqueous electrolytic solution of the present invention may further contain a film-forming agent.
Specific examples of the film-forming agent include carbonate compounds such as vinylene carbonate, vinylethyl carbonate and methylphenyl carbonate; alkene sulfides such as ethylene sulfide and propylene sulfide; and sulton compounds such as 1,3-propane sulton and 1,4-butane sulton. Examples thereof include acid anhydrides such as maleic anhydride and succinic anhydride.

An overcharge inhibitor such as diphenyl ether or cyclohexylbenzene may be further added to the non-aqueous electrolytic solution.
When the above various additives are used, the total content of the additives is the entire non-aqueous electrolyte solution so as not to adversely affect other battery characteristics such as increase in initial irreversible capacity, low temperature characteristics, and decrease in rate characteristics. However, it can be usually 10% by mass or less, and more preferably 8% by mass or less, more preferably 5% by mass or less, and particularly preferably 2% by mass or less.

Further, as the electrolyte, a polymer solid electrolyte which is a conductor of an alkali metal cation such as lithium ion can also be used.
Examples of the polymer solid electrolyte include those in which a Li salt is dissolved in the above-mentioned polyether-based polymer compound, and a polymer in which the terminal hydroxy group of the polyether is replaced with an alkoxide.

<Preparation of electrolyte>
The non-aqueous electrolyte solution of the present invention can be prepared by dissolving a sulfone compound having a structure represented by the above general formula (I), an electrolyte, and other compounds as necessary in a non-aqueous solvent. ..
In the preparation of a non-aqueous electrolytic solution, it is preferable that each raw material is dehydrated in advance in order to reduce the water content of the electrolytic solution. Usually, it is preferable to dehydrate to 50 ppm or less, preferably 30 ppm or less, and particularly preferably 10 ppm or less. Further, after preparing the electrolytic solution, dehydration, deoxidation treatment and the like may be carried out.

[Lithium-ion battery]
The lithium ion battery of the present invention can take various configurations, but the basic configuration is an embodiment including a positive electrode and a negative electrode capable of storing and releasing lithium ions, and the above-mentioned electrolytic solution of the present invention. Usually, it is obtained by storing the positive electrode and the negative electrode in a case via a porous membrane impregnated with an electrolytic solution.
The lithium ion battery of the present invention is characterized by containing a vinyl sulfone compound in the electrolytic solution.
The shape of the lithium ion battery of the present invention is not particularly limited, and may be any of a cylindrical type, a square type, a laminated type, a coin type, a large size, and the like.

<Negative electrode>
The negative electrode according to the present invention may take various aspects, but basically, it includes a current collector and an active material layer formed on the current collector, and the active material layer serves as a negative electrode active material. It is preferable that the embodiment is contained. The active material layer preferably further contains a binder.

(Negative electrode current collector)
The negative electrode current collector according to the present invention is not particularly limited, and known ones can be used. Specific examples thereof include rolled copper foil, electrolytic copper foil, and metal thin films such as stainless steel foil.
The thickness of the negative electrode current collector can be in the range of 4 to 30 μm. It is preferably in the range of 6 to 20 μm.

(Negative electrode active material)
The negative electrode active material is not particularly limited as long as it can occlude and release lithium ions. Specific examples thereof include carbonaceous materials, alloy-based materials, lithium-containing metal composite oxide materials, and the like.
These negative electrode active materials may be used alone or in combination of two or more. Of these, carbonaceous materials and alloy-based materials are preferable, and carbonaceous materials are more preferable.
Among the carbonaceous materials, those in which the surface of amorphous carbon material, graphite, or graphite is coated with amorphous carbon as compared with graphite are preferable, and in particular, the surface of graphite or graphite is more amorphous than that of graphite. The carbon-coated material generally has a high energy density and is preferable.
Among the negative electrode active materials containing these carbonaceous materials, since the capacity per unit mass is large when made into a battery, it contains at least one atom selected from the group consisting of Si atom, Sn atom and Pb atom. Carbonaceous material active material is more preferable.

As for graphite, it is preferable that the d value (interlayer distance) of the lattice plane (002 plane) obtained by X-ray diffraction by the Gakushin method is 0.335 to 0.338 nm, particularly 0.335 to 0.337 nm. The crystallite size (Lc) determined by X-ray diffraction by the Gakushin method is usually 10 nm or more, preferably 50 nm or more, and particularly preferably 100 nm or more.
The ash content is usually 1% by mass or less, preferably 0.5% by mass or less, and particularly preferably 0.1% by mass or less.

It is preferable that the surface of the graphite is coated with amorphous carbon by using graphite having a d value of the lattice plane (002 plane) of 0.335 to 0.338 nm in X-ray diffraction as a core material and forming the surface thereof. A carbonaceous material having a larger d value of the lattice plane (002 plane) in X-ray diffraction than the nuclear material is attached, and the d value of the lattice plane (002 plane) in X-ray diffraction is larger than that of the nuclear material and the nuclear material. The ratio to the carbonaceous material having a large mass ratio is 99/1 to 80/20 in terms of mass ratio. By using this, it is possible to manufacture a negative electrode having a high capacity and hardly reacting with an electrolytic solution.

The particle size of the carbonaceous material is a median diameter obtained by a laser diffraction / scattering method and is in the range of 1 to 100 μm, preferably 3 to 50 μm, and more preferably 5 to 40 μm.
The specific surface area of the carbonaceous material by the BET method is in the range of 0.3 to 25.0 m ² / g, preferably 0.8 to 10.0 m ² / g.

The carbonaceous material was analyzed by Raman spectrum using argon ion laser light, and the peak intensity of peak _PA in the range of 1570 to 1620 cm ^-1 was changed to _IA , peak P in the range of 1300 to 1400 cm ^-1 . When the peak intensity of _B is _IB , the R value (= _IB / _IA ) represented by the ratio of _IB and _IA is preferably in the range of 0.01 to 0.7. Further, it is preferable that the half width of the peak in the range of 1570 to 1620 cm ^-1 is 26 cm ^-1 or less, particularly 25 cm ^-1 or less.

The alloy-based material is not particularly limited as long as it can store and release lithium, and is a simple substance metal and alloy that forms a lithium alloy, or their oxides, carbides, nitrides, silides, sulfides, and phosphates. It may be any of the compounds such as. A material containing a single metal and an alloy forming a lithium alloy is preferable, and a material containing a metal / semi-metal element of Groups 13 and 14 (that is, excluding carbon) is more preferable, and further, aluminum, silicon, and aluminum, silicon, and materials are more preferable. It is preferable that it is a single metal of tin (these may be referred to as "specific metal elements" below), and an alloy or compound containing these elements.

As an example of a negative electrode active material having at least one element selected from specific metal elements, a single metal of any one specific metal element, an alloy consisting of two or more specific metal elements, one type or two or more types Specified metal element and other alloys consisting of one or more metal elements, compounds containing one or more specified metal elements, and oxides, carbides, nitrides, and nitrides of the compounds. Examples include complex compounds such as silicates, sulfides and phosphodies.
By using these metal simple substances, alloys or metal compounds as the negative electrode active material, it is possible to increase the capacity of the battery.

Further, a compound in which these composite compounds are complicatedly bonded to several kinds of elements such as elemental metals, alloys, and non-metal elements can be mentioned as an example. More specifically, for example, in silicon and tin, an alloy of these elements and a metal that does not operate as a negative electrode can be used. Further, for example, in tin, a complex compound containing 5 to 6 kinds of elements in combination with a metal that acts as a negative electrode other than tin and silicon, a metal that does not act as a negative electrode, and a non-metal element is also used. Can be done.

Among these negative electrode active materials, since the capacity per unit mass is large when made into a battery, a single metal of any one specific metal element, an alloy of two or more specific metal elements, and oxidation of a specific metal element. Substances, carbides, nitrides and the like are preferable, and in particular, silicon and / or tin metal alone, alloys, oxides, carbides, nitrides and the like have a large capacity per unit mass and are preferable.
Further, the following compounds containing silicon and / or tin are also preferable because they are superior in cycle characteristics, although they are inferior in capacity per unit mass to those using elemental metals or alloys.

The elemental ratio of silicon and / or tin to oxygen is in the range of 0.5 to 1.5, preferably 0.7 to 1.3, more preferably 0.9 to 1.1. Or an oxide of tin.
-Silicon and / or silicon and / or silicon having an elemental ratio of tin to nitrogen in the range of 0.5 to 1.5, preferably 0.7 to 1.3, and more preferably 0.9 to 1.1. / Or tin nitride.
-Silicon and / or tin having an elemental ratio of silicon and / or tin to carbon of 0.5 to 1.5, preferably 0.7 to 1.3, and more preferably 0.9 to 1.1. Carbide.

Further, these alloy-based materials may be powdery or thin-film, and may be crystalline or amorphous.
The average particle size of the alloy-based material is not particularly limited in order to exhibit the effect of the present invention, but is in the range of 0.1 to 50 μm, preferably 1 to 20 μm, and particularly preferably 2 to 10 μm. This is to prevent the expansion of the electrode and the deterioration of the cycle characteristics. In addition, this is to fully develop the performance such as current collection and capacity.

The lithium-containing metal composite oxide material used as the negative electrode active material is not particularly limited as long as it can store and release lithium, but is also referred to as a composite oxide of lithium and titanium (hereinafter, also referred to as “lithium titanium composite oxide”). ) Is preferable.
Further, lithium or a part of titanium of the lithium titanium composite oxide is selected from the group consisting of other metal elements such as Na, K, Co, Al, Fe, Mg, Cr, Ga, Cu, Zn and Nb. Those substituted with at least one element are also preferable.

Further, it is a lithium titanium composite oxide represented by Li _{x Ty M z O 4} , and has 0.7 ≦ x ≦ 1.5, 1.5 ≦ y ≦ 2.3, and 0 ≦ z ≦ 1.6. It is preferable that the lithium ion has a stable structure during storage and release (M is from the group consisting of Na, K, Co, Al, Fe, Mg, Cr, Ga, Cu, Zn and Nb. Represents at least one element selected.)
Among them, the structure in which x, _y , and z of the lithium titanium composite oxide represented by Li _x Ty M _z O ₄ satisfy any of the following (a) to (c) is the structure of the battery performance. It is particularly preferable because it has a good balance.

(A) 1.2 ≦ x ≦ 1.4, 1.5 ≦ y ≦ 1.7, z = 0
(B) 0.9 ≦ x ≦ 1.1, 1.9 ≦ y ≦ 2.1, z = 0
(C) 0.7 ≦ x ≦ 0.9, 2.1 ≦ y ≦ 2.3, z = 0
Particularly preferred representative compositions are Li _4/3 Ti _5/3 O ₄ in (a), Li ₁ Ti ₂ O ₄ in (b), and Li _4/5 Ti _11/5 O ₄ in (c). ..
As for the structure when Z ≠ 0, for example, Li _4/3 Ti _4/3 Al _1/3 O ₄ is preferable.
In the present invention, the negative electrode active material disclosed in JP-A-2015-173107 can also be used.

(Negative electrode binder)
The binder for the negative electrode is not particularly limited, but a binder having an olefinically unsaturated bond in the molecule is preferable. Specific examples include styrene-butadiene rubber, styrene / isoprene / styrene rubber, acrylonitrile-butadiene rubber, butadiene rubber, and ethylene / propylene / diene copolymers.

By using a binder having such an olefinically unsaturated bond, the swelling property of the active material layer with respect to the electrolytic solution can be reduced. Of these, styrene-butadiene rubber is preferable because of its availability.
By using a binder having an olefinically unsaturated bond in such a molecule in combination with a negative electrode active material, the mechanical strength of the negative electrode plate can be increased. When the mechanical strength of the negative electrode plate is high, deterioration of the negative electrode due to charging and discharging is suppressed, and the cycle life can be extended.

The binder having an olefinically unsaturated bond in the molecule preferably has a large molecular weight and / or a large proportion of unsaturated bonds.
As the molecular weight of the binder, the weight average molecular weight can be usually 10,000 or more, and can be usually 1 million or less. Within this range, both mechanical strength and flexibility can be controlled within a good range. The weight average molecular weight is preferably in the range of 50,000 or more, and preferably 300,000 or less.

As the ratio of olefinically unsaturated bonds in the molecule of the binder, the number of moles of olefinically unsaturated bonds per 1 g of the total binder is usually in the range of 2.5 × 10 ^-7 to 5 × 10 ^-6 mol. Can be done. Within this range, the effect of improving the strength can be sufficiently obtained, and the flexibility is also good.

Further, for a binder having an olefinically unsaturated bond, the degree of unsaturation can be usually in the range of 15 to 90%. The degree of unsaturation is preferably in the range of 20-80%. In the present specification, the degree of unsaturation represents the ratio (%) of double bonds to the repeating unit of the polymer.
As the binder, a binder having no olefinically unsaturated bond can also be used. By using a binder having an olefinically unsaturated bond in the molecule and a binder having no olefinically unsaturated bond in combination, improvement in coatability can be expected.

When the binder having an olefinically unsaturated bond is 100% by mass, the mixing ratio of the binder having no olefinically unsaturated bond is usually 150% by mass or less in order to suppress the decrease in the strength of the active material layer. It can be, preferably 120% by mass or less.

Examples of binders having no olefinic unsaturated bond include thickening polysaccharides such as methyl cellulose, carboxymethyl cellulose, starch, carrageenan, purulan, guar gum, and zansan gum (xanthan gum); polyethers such as polyethylene oxide and polypropylene oxide; Vinyl alcohols such as polyvinyl alcohol and polyvinyl butyral; polyacids such as polyacrylic acid and polymethacrylic acid or metal salts thereof; fluoropolymers such as polyvinylidene fluoride; alkene polymers such as polyethylene and polypropylene or their co-weights. Coalescence etc. can be mentioned.

(Negative electrode conductive auxiliary agent)
The active material layer may contain a conductive auxiliary agent in order to improve the conductivity of the negative electrode.
The conductive auxiliary agent is not particularly limited, and examples thereof include carbon black such as acetylene black, ketjen black, and furnace black, Cu and Ni having an average particle size of 1 μm or less, and fine powder made of an alloy thereof.
The amount of the conductive auxiliary agent added is preferably 10% by mass or less with respect to the negative electrode active material.

The negative electrode according to the present invention can be formed by dispersing a negative electrode active material and, in some cases, a binder and / or a conductive auxiliary agent in a dispersion medium to form a slurry, which is applied to a current collector and dried. As the dispersion medium, an organic solvent such as alcohol or water can be used.
The current collector to which the slurry is applied is not particularly limited, and known current collectors can be used. Specific examples thereof include rolled copper foil, electrolytic copper foil, and metal thin films such as stainless steel foil.

The thickness of the negative electrode active material layer (hereinafter, also simply referred to as “active material layer”) obtained by applying and drying the slurry is sufficient for practicality as a negative electrode and a high-density current value. It can be within the range of 5 to 200 μm from the viewpoint of the function of storage and release. It is preferably in the range of 20 to 100 μm.

The thickness of the active material layer may be adjusted to the above range by pressing after applying and drying the slurry.
The density of the negative electrode active material in the active material layer varies depending on the application, but is in the range of 1.10 to 1.65 g / cm ³ in applications where input / output characteristics are important, such as in-vehicle applications and power tool applications. Is preferable.

Within this range, it is possible to avoid an increase in contact resistance between particles due to too low a density, and on the other hand, it is possible to suppress a decrease in rate characteristics due to too high a density.
On the other hand, in applications where capacity is important, such as applications for mobile devices such as mobile phones and personal computers, the range is usually preferably in the range of 1.45 to 1.90 g / cm ³ .

Within this range, it is possible to avoid a decrease in battery capacity per unit volume due to too low density, and on the other hand, it is possible to suppress a decrease in rate characteristics due to too high density.

<Positive electrode>
The positive electrode according to the present invention may take various aspects, but basically, it includes a current collector and an active material layer formed on the current collector, and the active material layer serves as a positive electrode active material. It is preferable that the embodiment is contained. The active material layer preferably further contains a binder.

(Positive current collector)
The positive electrode current collector according to the present invention is not particularly limited, and known ones can be used. Specific examples thereof include aluminum, nickel and stainless steel (SUS).
The thickness of the positive electrode current collector can be in the range of 4 to 30 μm. It is preferably in the range of 6 to 20 μm.

(Positive electrode active material)
The positive electrode active material is not particularly limited as long as it can store and release lithium ions during charging and discharging. A substance containing lithium and at least one transition metal is preferable, and examples thereof include a lithium transition metal composite oxide and a lithium-containing transition metal phosphoric acid compound.

The transition metal of the lithium transition metal composite oxide is preferably V, Ti, Cr, Mn, Fe, Co, Ni, Cu or the like, and specific examples thereof include a lithium-cobalt composite oxide such as LiCoO ₂ and LiNiO ₂ . Lithium-nickel composite oxides, lithium-manganese composite oxides such as LiMnO ₂ , LiMn ₂ O ₄ , Li ₂ MnO ₃ , etc., and some of the transition metal atoms that are the main constituents of these lithium transition metal composite oxides are Al and Ti. , V, Cr, Mn, Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Si and the like substituted with other metals.
Among the substituted ones, LiNi _1-ab Mn _a Co _b O ₂ (a and b represent numbers 0 or more and less than 1, except when both a and b are 0), LiNi _1-c . _-D-e Co _c Al _d Mg _e O ₂ (c, d, e represent numbers 0 or more and less than 1, except when c, d, e are both 0) is preferable, and LiNi _{1- ab} Mn _a Co _b O ₂ (0 ≦ a <0.4, 0 ≦ b <0.4), LiNi _1-c-d-e Co _c Al _d Mg _e O ₂ (0 ≦ c <0. 3, 0 ≦ d <0.1, 0 ≦ e <0.05) is preferable, and in particular, LiNi _1/3 Co _01/3 Mn _1/3 O ₂ and LiNi _0.5 Co _0.3 Mn _0.2 O. ₂ , LiNi _0.5 Mn _0.5 O ₂ , LiNi _0.85 Co _0.10 Al _0.05 O ₂ , LiNi _0.85 Co _0.10 Al _0.03 Mg _0.02 O ₂ are preferable.

As the transition metal of the lithium-containing transition metal phosphoric acid compound, V, Ti, Cr, Mn, Fe, Co, Ni, Cu and the like are preferable, and specific examples thereof are, for example, LiFePO ₄ , Li ₃ Fe ₂ (PO ₄ ). _3. Iron phosphates such as LiFeP ₂ O ₇ , cobalt phosphates such as LiCoPO ₄ , and some of the transition metal atoms that are the main constituents of these lithium transition metal phosphate compounds are Al, Ti, V, Cr, Mn. , Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Nb, Si and the like substituted with other metals.

These positive electrode active materials may be used alone or in combination of two or more.
Further, it is also possible to use a substance (surface adhering substance) having a composition different from the substance constituting the main positive electrode active material attached to the surface of these positive electrode active materials. Surface adhering substances include aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide, bismuth oxide and other oxides, lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate and calcium sulfate. , Sulfates such as aluminum sulfate, carbonates such as lithium carbonate, calcium carbonate, magnesium carbonate and the like.

The amount of the surface-adhering substance is not particularly limited in order to exhibit the effect of the present invention, but is preferably in the range of 0.1 to 20 mass ppm, more preferably 1 to 2 with respect to the positive electrode active material. It is used within the range of 10 ppm. The surface-adhering substance can suppress the oxidation reaction of the non-aqueous electrolyte solution on the surface of the positive electrode active material, and can improve the battery life.

(Positive electrode conductive aid)
A conductive auxiliary agent may be contained in the positive electrode active material layer in order to improve the conductivity of the positive electrode. The conductive auxiliary agent is not particularly limited, and examples thereof include carbon powders such as acetylene black, carbon black, and graphite, fibers, powders, and foils of various metals.

(Positive binder)
The binder for the positive electrode is not particularly limited, and a known binder can be arbitrarily selected and used. Examples include inorganic compounds such as silicate and water glass, and resins having no unsaturated bond such as Teflon (registered trademark) and polyvinylidene fluoride. Of these, a resin having no unsaturated bond is preferable because it does not easily decompose during the oxidation reaction.
The weight average molecular weight of the binder can usually be in the range of 10,000 to 3 million, preferably in the range of 100,000 to 1,000,000.

<Others>
In addition to the above-mentioned various materials, the electrode may contain a thickener, a conductive material, a filler, or the like in order to increase mechanical strength and electrical conductivity.
Examples of the thickener include carboxymethyl cellulose, methyl cellulose, hydroxymethyl cellulose, ethyl cellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, gazein and the like.

(Method of manufacturing electrodes)
The electrode may be manufactured by a conventional method. For example, it can be formed by adding a binder, a thickener, a conductive material, a solvent, or the like to a negative electrode or a positive electrode active material to form a slurry, applying the slurry to a current collector, drying the slurry, and then pressing the slurry.
In addition, an active material with a binder, a conductive material, etc. added can be rolled into a sheet electrode as it is, a pellet electrode can be obtained by compression molding, or an electrode material can be placed on a current collector by means of vapor deposition, sputtering, plating, etc. It is also possible to form a thin film.

When graphite is used as the negative electrode active material, the density of the negative electrode active material layer after drying and pressing is preferably in the range of 1.0 to 2.2 g / cm ³ . It is preferably in the range of 1.3 to 1.9 g / cm ³ . This is to prevent an increase in the initial irreversible capacity due to the destruction of the negative electrode active material particles, and to prevent the permeability of the electrolytic solution into the active material layer from being lowered and the high rate charge / discharge characteristics from being deteriorated. Further, this is to prevent the capacity per unit volume from being reduced due to the decrease in conductivity between the active materials.
The density of the positive electrode active material layer after drying and pressing is preferably in the range of 1.5 to 5.0 g / cm ³ . More preferably, it is in the range of 2.2 to 4.0 g / cm ³ . This is to prevent deterioration of the high rate charge / discharge characteristics due to a decrease in the permeability of the electrolytic solution into the active material layer. This is also to prevent deterioration of high rate charge / discharge characteristics due to a decrease in conductivity between active materials.

<Separator, exterior body>
A porous film (separator) is interposed between the positive electrode and the negative electrode to prevent a short circuit. In this case, the electrolytic solution is used by impregnating the porous membrane. The material and shape of the porous membrane are not particularly limited as long as they are stable in the electrolytic solution and have excellent liquid retention properties, and a porous sheet or a non-woven fabric made from a polyolefin such as polyethylene or polypropylene is preferable.
The material of the outer body of the battery used for the lithium ion battery of the present invention is also arbitrary, and nickel-plated iron, stainless steel, aluminum or an alloy thereof, nickel, titanium, a laminated film and the like are used.
The operating voltage of the above-mentioned lithium ion battery of the present invention is usually in the range of 2 to 6V.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. Although the display of "parts" or "%" is used in the examples, it represents "parts by mass" or "% by mass" unless otherwise specified.

[Example 1]: Storage stability in solution (ethylene carbonate) <Preparation of solution 1>
After dissolving the above-mentioned example compound 1 (5 g) in ethylene carbonate (100 mL), the solution was filtered through activated carbon to obtain an ethylene carbonate solution of the example compound 1. After storing this solution at 25 ° C. for 30 days in a dark place, the presence or absence of precipitates was visually confirmed. The evaluation results are shown in Table I below. In the table, no precipitate is indicated by ◯, and presence of precipitate is indicated by ×.

<Preparation of solutions 2 to 17>
Solutions 2 to 17 were prepared in the same manner except that the exemplary compound 1 used in the preparation of the solution 1 was changed to the exemplary compounds shown in Table I below, and the presence or absence of precipitates was confirmed.

<Preparation of solution 18>
A solution 18 was prepared in the same manner except that the exemplary compound 1 used in the preparation of the solution 1 was changed to the comparative compound 1 below, and the presence or absence of a precipitate was confirmed.

From the results shown in Table I, it is confirmed that the solution containing the vinyl sulfone compound of the present invention has no precipitate and is excellent in storage stability.

[Example 2]: Storage stability (capacity) of the battery
<Preparation of non-aqueous electrolyte solution>
Under a dry argon atmosphere, 0.05% by mass of the above-mentioned exemplary compound 1 and 2% by mass of vinylene carbonate were mixed with a mixed solvent of ethylene carbonate and ethylmethyl carbonate (mass ratio 3: 7). Then, the sufficiently dried LiPF ₆ was dissolved at a ratio of 1 mol / liter to obtain a non-aqueous electrolyte solution.

<Manufacturing of positive electrode>
N-Methylpyrrolidone solution containing 94% by mass of lithium cobalt composite oxide (LiCoO ₂ ) as a positive electrode active material, 3% by mass of acetylene black as a conductive auxiliary agent, and 3% by mass of polyvinylidene fluoride (PVdF) as a binder. Inside, they were mixed with a disperser to form a slurry. This was uniformly applied to both sides of an aluminum foil having a thickness of 15 μm, dried, and then pressed so that the density of the positive electrode active material layer was 3.1 g / cm ³ to prepare a positive electrode.

<Manufacturing of negative electrode>
98 parts by mass of artificial graphite powder KS-44 (manufactured by Timcal Co., Ltd., trade name) as a negative electrode active material, 100 mass by mass of an aqueous dispersion of sodium carboxymethyl cellulose (concentration of sodium carboxymethyl cellulose 1% by mass) as a thickener and a binder, respectively. 2 parts by mass and 2 parts by mass of an aqueous dispersion of styrene-butadiene rubber (concentration of styrene-butadiene rubber 50% by mass) were added and mixed with a disperser to form a slurry. This slurry was uniformly applied to one side of a copper foil having a thickness of 10 μm, dried, and then pressed so that the density of the negative electrode active material was 1.6 g / cm ³ to prepare a negative electrode.

<Manufacturing of lithium-ion battery 1>
The above positive electrode, negative electrode, and polyethylene separator were laminated in this order of positive electrode, separator, negative electrode, separator, and positive electrode to prepare a battery element. After inserting this battery element into a bag made of a laminated film in which both sides of aluminum (thickness 40 μm) are coated with a resin layer while projecting positive and negative terminals, the above non-aqueous electrolyte solution is injected into the bag. , Vacuum-sealed to produce a sheet-shaped lithium-ion battery 1.
The sheet-shaped lithium-ion battery 1 was used for the evaluation shown below, and the evaluation results are shown in Table II below.

<Initial discharge capacity evaluation test>
The sheet-shaped lithium ion battery produced above was charged at 25 ° C. with a constant current corresponding to 0.2 C to 4.1 V, and then discharged to 3 V with a constant current of 0.2 C. This was performed for 3 cycles to stabilize the battery. Next, after charging to 4.2 V with a constant current of 0.7 C, charging is performed with a constant voltage of 4.2 V until the current value reaches 0.05 C, and the battery is discharged to 3 V with a constant current of 0.2 C. The initial discharge capacity was calculated.
Here, 1C represents a current value for discharging the reference capacity of the battery in 1 hour, and 0.2C represents, for example, a current value of 1/5 of that.

<High temperature storage characteristic evaluation test>
The lithium ion battery for which the initial discharge capacity evaluation test was completed was charged at 25 ° C. with a constant current of 0.7 C to 4.2 V, and then charged with a constant voltage of 4.2 V until the current value became 0.05 C. Then, it was stored at 85 ° C. for 1 day.
After cooling the lithium-ion battery to 25 ° C, discharge it to 3V at a constant current of 0.2C at 25 ° C, measure the remaining capacity after the high-temperature storage characteristic evaluation test, and measure the remaining capacity after full charge before storage. The remaining capacity after storage was calculated as a percentage (%).
Remaining capacity = (discharge capacity after storage / initial discharge capacity) x 100 (%)

<Manufacturing of lithium-ion battery 2>
In the production of the lithium ion battery 1, the same as that of the lithium ion battery 1 except that the content of the exemplary compound 1 contained in the non-aqueous electrolyte solution is 0.5% by mass instead of 0.05% by mass. A lithium-ion battery 2 was produced and evaluated in the same manner as the lithium-ion battery 1.

<Manufacturing of lithium-ion battery 3>
In the production of the lithium ion battery 1, the same as that of the lithium ion battery 1 except that the content of the exemplary compound 1 contained in the non-aqueous electrolyte solution is 1.0% by mass instead of 0.05% by mass. A lithium-ion battery 3 was produced and evaluated in the same manner as the lithium-ion battery 1.

<Manufacturing of lithium-ion batteries 4 to 19>
In the production of the lithium ion battery 3, lithium ion batteries 4 to 19 were produced in the same manner as the lithium ion battery 3 except that the exemplary compounds 1 were replaced as shown in Table II below, respectively, and the same as the lithium ion battery 3. Was evaluated.

<Manufacturing of Lithium Ion Battery 20>
In the production of the lithium ion battery 3, the lithium ion battery 20 was produced in the same manner as the lithium ion battery 3 except that the exemplary compound 1 was replaced with the comparative compound 1, and the same evaluation as that of the lithium ion battery 3 was performed.

From the results shown in Table II, it is confirmed that the lithium ion battery produced by using the vinyl sulfone compound of the present invention has an increased residual capacity after high temperature storage and improved high temperature storage characteristics.

[Example 3]: Cycle test <Preparation of non-aqueous electrolyte solution 1>
Under a dry argon atmosphere, 1% by mass of the above-mentioned exemplary compound 1 was mixed with a mixed solvent (mass ratio 1: 1) of ethylene carbonate (EC) and diethyl carbonate (DEC). Then, the sufficiently dried LiPF ₆ was dissolved at a ratio of 1 mol / liter to obtain a non-aqueous electrolyte solution.

<Preparation of non-aqueous electrolyte solution 2>
Under a dry argon atmosphere, 1% by mass of the above-mentioned exemplary compound 1 was mixed with a mixed solvent (mass ratio 1: 1: 1) of ethylene carbonate (EC), dimethyl carbonate (DMC) and diethyl carbonate (DEC). Then, the sufficiently dried LiPF ₆ was dissolved at a ratio of 1 mol / liter to obtain a non-aqueous electrolyte solution.

<Manufacturing of positive electrode 1>
Lithium nickel cobalt manganese composite oxide (Nichia ternary highNi type-LiNi _5/10 Co _2/10 Mn _3/10 O ₂ ) 93% by mass, which is a positive electrode active material, and acetylene black 3 as a conductive auxiliary agent. Mass% and 3 mass% of polyvinylidene fluoride (PVdF) as a binder were mixed with a disperser in an N-methylpyrrolidone solution to form a slurry. This was uniformly applied to both sides of an aluminum foil having a thickness of 15 μm, dried, and then pressed so that the density of the positive electrode active material layer was 3.1 g / cm ³ to prepare a positive electrode.

<Manufacturing of negative electrode 1>
As a negative electrode active material, 93 parts by mass of artificial graphite powder KS-44 (manufactured by Timcal Co., Ltd., trade name) was mixed with 8 parts by mass of PVdF, N-methylpyrrolidone was added, and the mixture was mixed with a disperser to form a slurry. This slurry was uniformly applied to one side of a copper foil having a thickness of 10 μm, dried, and then pressed so that the density of the negative electrode active material was 1.6 g / cm ³ to prepare a negative electrode.

<Manufacturing of negative electrode 2>
As a negative electrode active material, 91 parts by mass of artificial graphite powder containing SiO (manufactured by Nippon Carbon Co., Ltd.) was mixed with 9 parts by mass of PVdF, N-methylpyrrolidone was added, and the mixture was mixed with a disperser to form a slurry. This slurry was uniformly applied to one side of a copper foil having a thickness of 10 μm, dried, and then pressed so that the density of the negative electrode active material was 1.6 g / cm ³ to prepare a negative electrode.

<Manufacturing of lithium-ion battery 21>
The positive electrode 1, the negative electrode 1, and the polyethylene separator were laminated in this order of the positive electrode, the separator, the negative electrode, the separator, and the positive electrode to prepare a battery element. After inserting this battery element into a bag made of a laminated film in which both sides of aluminum (thickness 40 μm) are coated with a resin layer while projecting positive and negative terminal terminals, the non-aqueous electrolyte solution 1 is injected into the bag. Then, vacuum sealing was performed to prepare a sheet-shaped lithium ion battery 1.
The sheet-shaped lithium-ion battery 21 was used for the evaluation shown below, and the evaluation results are shown in Table III below.

<Cycle evaluation test>
The sheet-shaped lithium-ion battery produced above is charged at a constant current-constant voltage to a predetermined voltage at 0.2 C at 25 ° C. (hereinafter, appropriately referred to as "CCCV charging"), and then discharged to 3.0 V at 0.2 C. The charging / discharging cycle was repeated 100 times. The cutoff current during charging was 0.01 C. The capacity retention rate after 300 cycles was calculated by the following formula, and the cycle characteristics were evaluated using that value. The larger this value is, the less the cycle deterioration of the battery is. At the end of the first charge, the open circuit voltage between the battery terminals was measured.
Capacity retention rate after 300 cycles [%]
= 100th discharge capacity [mAh / g] / 1st discharge capacity [mAh / g] × 100

<Manufacturing of lithium-ion battery 22>
In the production of the lithium ion battery 21, lithium ions are produced in the same manner as the lithium ion battery 21 except that the content of the exemplary compound 1 contained in the non-aqueous electrolyte solution is 0.01% by mass instead of 1% by mass. A battery 22 was manufactured and evaluated in the same manner as the lithium ion battery 21.

<Manufacturing of lithium-ion battery 23>
In the production of the lithium ion battery 21, lithium ions are produced in the same manner as the lithium ion battery 21 except that the content of the exemplary compound 1 contained in the non-aqueous electrolyte solution is 4.95% by mass instead of 1% by mass. A battery 23 was manufactured and evaluated in the same manner as the lithium ion battery 21.

<Manufacturing of lithium-ion battery 24>
In the production of the lithium ion battery 21, the lithium ion battery 24 was produced in the same manner as the lithium ion battery 21 except that the negative electrode 1 was replaced with the negative electrode 2, and the same evaluation as that of the lithium ion battery 21 was performed.

<Manufacturing of lithium-ion battery 25>
In the production of the lithium ion battery 21, the lithium ion battery 25 was produced in the same manner as the lithium ion battery 21 except that the non-aqueous electrolytic solution 1 was replaced with the non-aqueous electrolytic solution 2, and the same as the lithium ion battery 21. Was evaluated.

<Manufacturing of lithium-ion batteries 26-28>
In the production of the lithium ion battery 21, the lithium ion batteries 26 to 28 are produced in the same manner as the lithium ion battery 21 except that the exemplary compound 1 contained in the non-aqueous electrolyte solution is replaced with the compound corresponding to Table III below. Then, the same evaluation as that of the lithium ion battery 21 was performed.

<Manufacturing of lithium-ion batteries 29 to 31>
In the production of the lithium ion battery 21, the lithium ion batteries 29 to 31 are produced in the same manner as the lithium ion battery 21 except that the exemplary compound 1 contained in the non-aqueous electrolyte solution is replaced with the compound corresponding to Table III below. Then, the same evaluation as that of the lithium ion battery 21 was performed.

<Manufacturing of lithium-ion battery 32>
In the production of the lithium ion battery 21, lithium ions are produced in the same manner as the lithium ion battery 21 except that the content of the exemplary compound 1 contained in the non-aqueous electrolyte solution is 0.05% by mass instead of 1% by mass. A battery 32 was manufactured and evaluated in the same manner as the lithium ion battery 21.

<Manufacturing of lithium-ion battery 33>
In the production of the lithium ion battery 21, the lithium ion battery 33 is the same as the lithium ion battery 21 except that the content of the exemplary compound 1 contained in the non-aqueous electrolyte solution is 6% by mass instead of 1% by mass. Was prepared and evaluated in the same manner as the lithium ion battery 21.

From the results shown in Table III, it is confirmed that the lithium ion battery produced by using the vinyl sulfone compound of the present invention has improved cycle characteristics. Further, as can be seen from the comparison between the battery 21 and the battery 24 using the vinyl sulfone compound of the present invention, it is possible to use a negative electrode active material made of a carbonaceous material containing a Si atom as the negative electrode material, and the capacity of the battery is high. It was confirmed that it is more preferable to obtain the effect of improving the cycle characteristics of the present invention.

[Example 4]: Initial charge / discharge efficiency test <Initial charge / discharge efficiency test>
The sheet-shaped lithium ion battery produced as described above was charged to 4.2 V at 25 ° C., discharged to 3 V, and conditioned until the capacity became stable. Then, the initial charge / discharge efficiency test was performed by repeating charging up to 4.2 V at a current value of 1.2 mA at 25 ° C. and discharging up to 3 V. At this time, ((i) + (ii) when the first discharge capacity is (i), the second discharge capacity is (ii), the first charge capacity is (iii), and the second charge capacity is (iv). )) / ((Iii) + (iv)) × 100 was defined as the “initial charge / discharge efficiency”.
A lithium-ion battery having the same configuration as the cycle test was prepared, and the initial charge / discharge efficiency was calculated.
The evaluation results are shown in Table IV.

From the results shown in Table IV, it is confirmed that the lithium ion battery produced by using the vinyl sulfone compound of the present invention also improves the initial charge / discharge efficiency.

The present invention is a vinyl sulfone compound or the like which is excellent in storage stability when stored for a long period of time in a non-aqueous solvent and can improve the decrease in capacity after a high temperature storage test when used in a lithium ion battery. It can be used.

Claims (15)

A vinyl sulfone compound having a structure represented by the following general formula (I) or a structure represented by the following general formula (IV) .

[In the general formula (I), A represents a cyclohexane ring, a benzene ring, a pyridine ring or a furan ring . R ₁ represents the following general formula (II) or the following general formula (III). ]

[In the general formula (II), R ₂ may be substituted with a hydrogen atom or a halogen atom, an alkyl group, a cycloalkyl group, a halogen atom or an alkyl group, an aryl group or an alkoxy group. , Aryloxy group or -NR ₄ R ₅ . R ₄ and R ₅ represent an alkyl group or an aryl group. -* Represents a bond with an oxygen atom.
In the general formula (III), R ₃ may be substituted with an alkenyl group, an alkynyl group, a halogen atom, an alkyl group or a cycloalkyl group, a halogen atom or an alkyl group, an aryl group, Represents an alkoxy group, an aryloxy group or -NR ₄ R ₅ . R ₄ and R ₅ represent an alkyl group or an aryl group. -* Represents a bond with an oxygen atom. ]

[In the general formula (IV), R ₆ represents an alkyl group having a hydrogen atom, an alkyl group, a vinylsulfonyl group, or an alkyl group having a halogen atom. R ₁ is synonymous with R ₁ in the general formula (I) . ] The vinyl sulfone compound according to claim ₁ , wherein R6 of the compound having a structure represented by the general formula (IV) is a hydrogen atom. In the general formula (I), R ₁ is represented by the general formula (II).
The vinyl sulfone compound according to claim 1 or 2 , wherein in the general formula (II), R ₂ represents an alkyl group having 1 to 6 carbon atoms or a fluorinated alkyl group having 1 to 6 carbon atoms. In the general formula (I), R ₁ is represented by the general formula (II).
The vinyl sulfone compound according to any one of claims 1 to 3 , wherein R ₂ is an alkyl group having 1 to 3 carbon atoms in the general formula (II). In the general formula (I), R ₁ is represented by the general formula (III).
The vinyl sulfone compound according to claim 1 or 2 , wherein in the general formula (III), R ₃ represents an alkyl group having 1 to 6 carbon atoms or a fluorinated alkyl group having 1 to 6 carbon atoms. The vinyl sulfone compound according to any one of claims 1 to 5 , wherein the compound having the structure represented by the general formula (I) is a material added to the electrolytic solution for a lithium ion battery. An electrolytic solution for a lithium ion battery containing the vinyl sulfone compound according to any one of claims 1 to 6 . The electrolytic solution for a lithium ion battery according to claim 7 , which contains at least one of a chain carbonate and a cyclic carbonate carbonate. The electrolytic solution for a lithium ion battery according to claim 7 or 8 , wherein the content of the vinyl sulfone compound is in the range of 0.01 to 5.0% by mass with respect to the total amount of the electrolytic solution. A lithium ion battery containing the vinyl sulfone compound according to any one of claims 1 to 6 in an electrolytic solution. The lithium ion battery according to claim 10 , further comprising a negative electrode made of an active material containing natural graphite or artificial graphite which is a carbonaceous material. The lithium ion battery according to claim 10 or 11 , further comprising a negative electrode made of a carbonaceous material active material containing at least one atom selected from the group consisting of Si atom, Sn atom and Pb atom. The lithium ion battery according to claim 12 , which has a negative electrode made of a carbonaceous material active material containing a Si atom. The lithium ion battery according to any one of claims 10 to 13 , which has a positive electrode made of an active material containing any one of a lithium transition metal composite oxide and a lithium-containing transition metal phosphoric acid compound. The lithium ion battery according to claim 14 , further comprising a positive electrode made of an active material containing a lithium transition metal composite oxide.